Biological effects of microgravity on brain cells were simulated by rotating chicken embryos in a clinostat during their hatch. Continuous fluorometry was used to study dynamic release of glutamate from brain cells of the embryonic chicks. The initial release rate, the induced release rate, the release content by KCl or by a single electric pulse and the total intracellular glutamate concentration have been compared between rotated and control groups. The results showed that there was no obvious difference in initial release rate between both rotated and controls. The total intracellular glutamate concentration increased significantly (P＜0.01) when E10 embryos were rotated for 4 h, and KCl- induced release rate and release content from brain cells of E10 embryos rotated for 24 h were higher than those from controls. However, there was no significant difference in the total intracellular glutamate concentration and the KCl- induced release rate, release content from brain cells of E13 embryos between rotated and their control groups. These results suggest that the releasing behaviors of neuro-transmitters from brain cells can be affected by microgravity and the influence is related to the age of the embryos. The dynamic process of glutamate release from brain cells induced by a singlee electric pulse shows that the release is related with a rapid increase of the intracellular ［Ca²⁺］_{i following the pulse.}